Gasoline container



April 22, 1952 c. w. TAYLOR GASOLINE CONTAINER Filed June 24, 1946 FIG.

IIL'

" SOLUBLE NYLON NYLON FABRIC NYLON FABRIC SOLUBLE I' NYLON FIG. 2

INVENTOR. CHARLES W. TAYLOR Patented Apr. 22, 1952 GASOLINE CONTAINER Charles W. Taylor, Akron, Ohio, assignor to Wingfoot Corporation ration of Delaware Akron, Ohio,4 a corpo- ApplicationrJune 24, 1`946,.Serial No.678,880 i This invention-relates to a new gasoline-resist@ ant coated fabric which is useful in the construction of containers for gasoline and other liquid hydrocarbons. The invention further relatcs'to light-weight containers which are impervious to gasoline and are especially suitable forA use in aircraft for holding aromatic fuels.

. In aircraft design and construction the provision of suitable containers for carrying the large quantities of fuel necessary for long nights has seen a serious problem. Metal containers which have been widely used are objectionable because of the excessive weight, nor can the airplane structure vbe effectively sealed to form a liquid containerl in itself. In order to overcome these diihculties there have been developed collapsible fabric containers so designed and constructed that they exactly lill the spaces available in the fuselage, wings, or other suitable parts of the airplane. By this means, the tanks or containers are supported by the structural elements of the aircraft and the gasoline is confined by a flexible light Weight barrier. The materials which have been inost successfully used in the construction of these collapsible tanks, known to the art as bladder cells, are woven textile fabrics impregnated with synthetic rubber of the GR-N type, the lfabric being vulcanized in contact with a calendered sheet of the same GR-N rubber. However, the bladder cells prepared from GR-N rubber have notbeen entirely satisfactory since, al-

though this material is the most resistant to, aromatic4 fuels of all synthetic rubbers, nevertheless itis` slightly solublein, and. isswelledor distorted byfcontactlwith, aromaticfuels. The cells of the prior art have. alsc been objectionable by reason ofthe thickness required. in the preparation of a thoroughly gasoline-impervious structure and its incident'weight. Further, thec'ells prepared from GR-N rubber are not sufliciently flexible to Withstand` the alternate inflation and' deflation as the gasoline is consumed and replenished, this deciency being especially noticeable at temperatures belowl 0 F., which are frequently encountered in aircraft operation.

Accordingly, one purpose of this invention is to providea new coated fabric useful in the manufacture of improved containers which are more resistant to liquid aromatic fuels than the previously known coated fabrics and containers. A further purpose; ofr thisA inventionv is to provide new coated fabrics which are lighter in weight and more resistant to the flexural, tensile and abrasive forces which are encountered in the nor, mal use of the containers.

1 Claim. (Cl. 150.90.57)

It has been discovered that a very greatly improved gasoline-resistant coated fabric can be prepared from a fabric woven-from cold-drawn polyamide filaments. The polyamide filaments are Well known and are generally referred to as nl/lon. Theser cold-drawn' polyamdes are of two general types: (A) Those prepared by the condensation of diamines with dicarboxylic acids or the corresponding esters, anhydrides, nitriles, acid chlorides, or amides, and (B) those .prepared by the condensation of monoaminomonocarboxylic acid or the corresponding derivatives, such as esters and lactams. Bothof these types of -polyarnides` are capable of fabrication into filaments which experience the-phenomenon known as cold-drafting, the filaments being strengthened and made less thermoplastic by stretching or elongation at temperatures below their melting points. The cold-drawingV propertyv is believed to be a characteristic of filaments; prepared from polyamides having a regularly recurring'molecular7 structure as shown by the: following structural:formulae:`

Although any dicarboxylic acid may housed, the longer chainacids, for example,` thcsehaving; at

lleast three atoms between the two carbonyl groups, are preferred. The diamines'used in the condensation with the dicarboxylic acids may be the hydrocarbon diamines, such as decamethylene diamine, hexamethylene diamine, and the oXahydrocarbon, diarnines and thiahydrocarbon diamines, such as- 3,3.'dianiinopropyl ether and 2 ;2diaminodiethyl suldc.

Type B of the polyamides capable'of being colddrawn are those prepared by the condensation of monoamino monocarboxylic acids or their de aration of fibers and woven fabrics. vamide interpolymers may be prepared from a if a dicarboxylic acid-diamine type of polyamide` is modified by the addition of a monoamino carboxylic acid or lactam, a very different type of polyamide resin is obtained. This type of polyamide is characterized by a linear molecular chain, which is not uniform throughout with respect to the presence of regularly recurring structural components. These polyamideswhich are not uniform molecularly, are not capable of being fabricated into filaments which are .sub-

ject to cold drawing, and therefore the polymers are more thermoplastic and are not influenced by cold working, as are the'polyamides of uniform molecular structure. The polyamides which are not uniform molecularly are known as interpolymers as distinguished from the uniform polymers ofthe type capable of being cold` drawn.

The interpolymers are not useful in the prep- The polymixture of dicarboxylic acids and a diamine, the

total proportion of the dicarboxylic acids being the approximate molar equivalent to the diamine; For example, one mole of succinic acid and two moles of sebacic acid may be condensed with three moles of decamethylene glycol. Similarly, a mixture of equimolar-proportions of a' dicarboxylic acid and of a diamine may beLmixed and condensed with any proportion of a mono' amino monocarboxylic acid. An example of this latter type of interpolymer is the polyamide prepared from one mole of adipic acid, one mole of hexamethylene diamine and two moles of epsilon caprolactam. It is quite apparent that the caprolactam need not be present in any particular molecular proportion so long ,as equivalent proportions of the dicarboxylic acid and the diamine .are used, since mixtures of condensing compounds will always contain approximately equal numbers of reactive amino groups and reactive carboxylic radicals. The polyamide interpolymers are well known commercial materials available on the market.

In accordance with this invention a fabric woven from cold drawn polyamide fibers is impregnated or otherwise coated with a polyamide interpolymer. Preferably the polyamide interpolymer is dissolved in a suitable solvent, such as ethyl alcohol-water solutions and spread on the woven polyamide fabric in such a manner as to force the polyamide interpolymer into the interstices of the fabric and to leave a uniform layer of polyamide on top of the woven fibers of cold drawn polyamide. The impregnated fabric may also be prepared in conventional calendering machinery where the solid polyamide interpolymer is rolled into the fabric and spread uniformly on both sides of the woven polyamide sheet. Alternatively, the polyamide interpolymer may' be dissolved in a suitable solvent, such as ethyl alcohol and mixture of water and ethyl alcohol, and the woven fabric immersed in said.

solution and dried. The latter operation is repeated a number of times until a sufficient quanart practice.

tity of polyamide is deposited in the interstices and on the outer surfaces of the woven polyamide bers. Frequently the immersion technique is used rst and is followed by aspreading operation.

The new polyamide-coated fabrics are valuable because of the resistance which they exhibit to the action of aromatic hydrocarbons. They are readily adaptable to the manufacture of containers for gasoline or other fuels and lubrication oils by reason of the fact that they can be joined readily by simple heat-sealing opera; tions. Bladder cells of irregular shapes may be made by fitting the prepared fabric around a form or template and pressing the over-lapped edges of the film with a heated tool. Other containers may be fabricated from the impregnated fabric by forming the container, within the supporting structures of the aircraft or other vehicle in which the lbladder cell.; is to be used. Thus, previously cut sections of the fabric are placed in position and heat-sealed by contacting the over-lapped edges under heat and pressure. The methods of fabricating containers from the new material will be understood by a skilled worker in this art.

The invention is illustrated in the accompany-V ing drawing in which Figure 1 shows a fuel cell made according to the present invention, Figure' 2 shows the material used in constructing the fuel cell and Figure 3 is a cross-section taken through the line 3--3 in Figure 1 and illustrating the method of assembling the fuel cell.

Further details of the practice of this invention are set forth with respect to the following example.

v Example An interpolymeric polyamide made by the condensation of approximatelylg percent by weight of hexamethylene diamine, 25 .percent of adipic acid, and 56 percent of epsilon-caprolactam, having an intrinsic viscosity of 1.56 and a melting point of 170 to 200 C. was used to coat and impregnate a 4 oz./sq. yd. twill weave fabric of cold dra-wn fibers of hexamethylene adipamide -polymer. To demonstrate thevalue of the new laminated composition both the new composition and the best available composition previously used for Vbladder cell fabrication were subjected to various physical tests. The previously used composition was a woven cotton fabric which was impregnated with a copolymer of about 60 to 'l5 percent of butadiene-1,3 and 25 to 40Ypercent of acrylonitrile, commercially known as GR-N synthetic rubber and then cemented to a calendered sheet of the same synthetic rubber.

The new composition described above, which weighed 0.075 lb./sq. ft. and was 0.018 inch in thickness, passed al1 Army and Navy requirements, while the prior art compositionV fabricated with sufficient thickness to comply with the tests VThe tensile strength in pounds per square inch and the elongation in percent were measured for .both the GR-N fabric and the interpolymeric polyamide impregnated polyamide fabric. The following table demonstrates that the composition of the invention is approximately percent better in tensile property and at the same time is more extensible than the previously used fabric.

Using a standard flexing test unit, 1 inch strips of both the prior art fabric and the new fabric i were tested by extending the samples to 10 percent elongation and flexing. The fabric prepared from GR-N and cotton cloth failed after 1,953 strokes, while the composition made in accordance with this invention did not fail until 94,000 strokes. This demonstrates that the invention is greatly superior in its ability to withstand continued flexing action.

A fabric prepared according to this invention and a fabric prepared from GR-N synthetic rubber were subjected to a standard abrasion test, both fabrics receiving 75,000 strokes. The prior art fabric was found to be completely abraded through the entire fabric, while the new polyamide fabric was only slightly Worn on the surface coating.

The new fabric made by coating polyamide woven fabric with polyamide interpolymer and the prior art fabric made from GRN synthetic rubber were both subjected to the action of a standard aromatic fuel in accordance with Army and Navy specification (ANT-49). After the fuel had stood in contact with the fabrics and had formed a saturated solution, the fuel samples were evaporated. The sample of fuel in contact with the polyamide composition contained 1.6 mg, per 100 ml., while the sample in contact with the prior art film of GR-N solids per 100 ml. of fuel.

Although the invention has been described with contained 1a mg. of 4 respect to specic modifications thereof and it is not intended that the details shall be construed as limitations upon the scope of the invention except to the extent incorporated in the following claim.

I claim:

A collapsible fabric fuel storage cell of light weight having thin flexible walls defining a fuel storage chamber, said walls being impervious to hydrocarbon fuels and resistant to the solvent action of such fuels and said walls consisting essentially of Woven fabric sections of cold-drawn fibers of a fiber-forming linear superpolyamide of uniform molecular chain structure and impregnated with, and having continuous coatings on both sides of a linear super-polyamide interpolymer, and the margins of said woven fabric sections being lapped and joined by autogenous fused seams of said coatings.

CHARLES W. TAYLOR.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,252,554 Carothers Aug. 12, 1941 2,269,125 Quenelle et a1 Jan. 6, 1942 2,301,128 Landefeld Nov. 3, 1942 2,302,332 Leekley Nov. 1'7, 1942 2,312,469 Freund Mar. 2, 1943 2,312,913 Kirby Mar. 2, 1943 2,355,084 Kurrle Aug. 8, 1944 2,370,419 Ray Feb. 27, 1945 2,381,739 Gray Aug. 7, 1945 2,421,613 Gray et al June 3, 1947 2,430,905 Bradley Nov. 18, 1947 FOREIGN PATENTS Number Country Date 583,873 Great Britain Aug. 20, 1941 

